One more thing. To whom is Macduff referring in the first sentence, "He has no children"? Perhaps he is saying this to Ross in response to Malcolm's hasty observation:

Merciful heaven!

What, man! Ne'er pull your hat upon your brows;

Give sorrow words. The grief that does not speak

Whispers the o'er fraught heart, and bids it break.

And also:

Be comforted.

Let's make us medicines of our great revenge,

To cure this deadly grief.

...

One more thing. To whom is Macduff referring in the first sentence, "He has no children"? Perhaps he is saying this to Ross in response to Malcolm's hasty observation:

Merciful heaven!

What, man! Ne'er pull your hat upon your brows;

Give sorrow words. The grief that does not speak

Whispers the o'er fraught heart, and bids it break.

And also:

Be comforted.

Let's make us medicines of our great revenge,

To cure this deadly grief.

Or maybe he is referring, ruefully, to himself and his present state of affairs. Or perhaps he is angrily referring to Macbeth who has no children and has murdered his. It's the kind of line a director has to grapple with.

Anyway, regardless of the reference, those four lines are spoken by a man who has just learned that his whole family has been wiped out, and he is on the verge of tears.

This set of lines comes from Macbeth. They are spoken by Macduff, the man who ends up as one of Macbeth's main enemies. He speaks these lines in Act IV, Scene 3 of the play.

The context here is that he has just found out that Macbeth has had his (Macduff's) whole family killed.

Macbeth has had Macduff's family killed in part because of the prophecy of the evil spirit conjured by the witches in Act IV, Scene 1. One of the spirits conjured told Macbeth that he should fear Macduff. One reaction of Macbeth's is to have the family killed.